CN103827259B - Phosphor materials and related devices - Google Patents

Abstract

The present invention provides a phosphor material comprising a blend of a first phosphor, a second phosphor and a third phosphor. The first phosphor comprises a composition having the general formula RE _{2- y} M _1+y A _2-y Sc _y Si _n-w Ge _w O _12+δ :Ce ³⁺ , wherein RE is selected from lanthanide ions or Y ³⁺ , wherein M is selected from Mg, Ca, Sr or Ba, A is selected from Mg or Zn, and wherein 0≤y≤2, 2.5≤n≤3.5, 0≤w≤1 and -1.5≤δ≤1.5. The second phosphor includes a complex fluoride doped with manganese (Mn ⁴⁺ ), and the third phosphor includes a phosphor composition having an emission peak in a range from about 520 nanometers to about 680 nanometers. The invention also provides a lighting device comprising such a phosphor material. In addition to the phosphor material, the lighting device also includes a light source.

Description

Phosphor materials and related devices

technical field

The present invention relates generally to phosphor blends for wavelength conversion, and in particular to phosphor blends for converting radiation emitted by light sources. More particularly, the present invention relates to phosphor blends for blue light emitting diodes (LEDs).

Background technique

Phosphors are luminescent materials that absorb radiant energy in one part of the electromagnetic spectrum and emit radiant energy in another part of the electromagnetic spectrum. An important class of phosphors consists of crystalline inorganic compounds of extremely high chemical purity and controlled composition, to which small amounts of other elements (called "activators") have been added to convert them into effective fluorescent materials. With the right combination of activators and inorganic compounds, the emitted color can be controlled. Most available known phosphors emit radiation in the visible part of the electromagnetic spectrum (also referred to herein as light) in response to excitation by electromagnetic radiation outside the visible range. For example, phosphors have been used in mercury vapor discharge lamps to convert ultraviolet (UV) radiation emitted by excited mercury to visible radiation. In addition, phosphors can be used in light emitting diodes (LEDs) to produce colored emissions that are not normally available from the LEDs themselves.

Light emitting diodes (LEDs) are semiconductor light emitters that are often used as replacements for other light sources, such as incandescent bulbs. They are particularly useful as display lights, warning lights and indicator lights, or in other applications requiring colored light. The color of light produced by an LED depends on the type of semiconductor material used in its manufacture. Colored LEDs are often used in toys, indicator lights, and other devices.

Colored semiconductor light-emitting devices, including light-emitting diodes and lasers (both generally referred to as LEDs in this specification), have been fabricated from III-V alloys such as gallium nitride (GaN). For GaN-based LEDs, light is typically emitted in the UV and/or blue range of the electromagnetic spectrum. Until recently, LEDs have been unsuitable for lighting applications requiring bright white light due to the inherent color of the light produced by LEDs.

Technologies have been developed for converting the light emitted by LEDs into usable light for lighting purposes. In one technique, LEDs are coated or covered with a phosphor layer. The phosphor absorbs the radiation produced by the LED and produces radiation of a different wavelength, for example in the visible range of the spectrum.

A combination of LED-generated light and phosphor-generated light can be used to generate white light. The most popular white LEDs are based on blue-emitting GaInN chips. Blue-emitting LEDs are coated with phosphors or phosphor blends including red, green, and blue-emitting phosphors that convert some of the blue radiation into a complementary color (e.g., yellow green launch). The sum of the light from the phosphor and the LED chip provides white light with a color point with corresponding color coordinates (x and y) and a correlated color temperature (CCT), and its spectral distribution is given by the color rendering index ( CRI) measured color rendering capabilities.

These white LEDs typically produce white light with a CRI between about 70 and about 80 for a tunable CCT greater than about 4000K. While such white LEDs are suitable for some applications, for many others it is desirable to produce white light with a higher CRI (greater than about 90) and lower CCT (less than 3000K).

Accordingly, it would be desirable to provide new and improved phosphor blends that produce white light with high CRI and high lumens for low CCT.

Contents of the invention

Briefly, most of the embodiments of the present invention provide a phosphor material comprising a blend of a first phosphor, a second phosphor and a third phosphor. The first phosphor comprises a composition having the general formula RE _2-y M _1+y A _2-y Sc _y Si _{n- w} Ge _w O _12+δ :Ce ³⁺ , where RE includes lanthanide ions or Y ^{3 +} , M includes Mg, Ca, Sr or Ba, A includes Mg or Zn, and 0≤y≤2, 2.5≤n≤3.5, 0≤w≤1 and -1.5≤δ≤1.5. The second phosphor includes a complex fluoride doped with manganese (Mn ⁴⁺ ), and the third phosphor includes a phosphorescent phosphor having an emission peak in a range from about 520 nanometers (nm) to about 680 nanometers (nm). body composition.

Some embodiments relate to a lighting device. The lighting device includes a light source and a phosphor material radiatively coupled to the light source. The phosphor material includes a blend of a first phosphor, a second phosphor, and a third phosphor. The first phosphor comprises a composition having the general formula RE _2-y M _1+y A _2-y Sc _y Si _nw Ge _w O _12+δ : Ce ³⁺ , wherein RE includes lanthanide ions or Y ^{3 +} , M includes Mg, Ca, Sr or Ba, A includes Mg or Zn, and 0≤y≤2, 2.5≤n≤3.5, 0≤w≤1 and -1.5≤δ≤1.5. The second phosphor includes a complex fluoride doped with manganese (Mn ⁴⁺ ), and the third phosphor includes a phosphor composition having an emission peak in a range of about 520 nm to about 680 nm.

Description of drawings

These and other features, aspects and advantages of the present invention will become better understood when read in the following detailed description when read with reference to the accompanying drawings, in which like numerals refer to like parts throughout:

Fig. 1 is a schematic cross-sectional view of a lighting device according to an embodiment of the present invention;

Fig. 2 is a schematic cross-sectional view of a lighting device according to an embodiment of the present invention;

Fig. 3 is a schematic cross-sectional view of a lighting device according to an embodiment of the present invention;

Fig. 4 is a schematic cross-sectional view of a lighting device according to an embodiment of the present invention;

Fig. 5 is a schematic cross-sectional view of a lighting device according to an embodiment of the present invention;

Figure 6 shows the emission spectrum of a phosphor blend using an excitation wavelength of 450 nm according to an exemplary embodiment of the present invention;

Figure 7 shows the emission spectrum of a phosphor blend using an excitation wavelength of 450 nm according to another exemplary embodiment of the present invention;

detailed description

Broad language, as used in this specification throughout the specification and claims, may be used to modify any quantitative expression that may vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms (eg, "about") is not to be limited to the precise value indicated. In some cases, the approximate language may correspond to the precision of the instrument used to measure the value.

In the following specification and the following claims, the singular forms "a" and "the" include plural referents unless the context clearly dictates otherwise.

As used in this specification, the terms "may" and "could" express the possibility of occurring within a set of circumstances; possess the indicated property, characteristic or function; One or more of the genders to qualify another verb. Thus, the use of "may" and "may" means that the modified term is clearly appropriate, capable or suitable for the stated performance, function or use, while taking into account that in some cases the modified term may sometimes be inappropriate, Capable or fit. For example, in some cases a result or property can be expected, while in other cases the result or property cannot occur, the characteristics are achieved by the terms "may" and "may be".

The terms "first", "second", etc. in this specification do not denote any order, quantity or importance, but are used to distinguish one element from another.

As used in this specification, the term "phosphor" or "phosphor material" or "phosphor composition" may be used to denote a single phosphor composition as well as a blend of two or more phosphor compositions. Phosphor blends may contain blue, red, yellow, orange and green phosphors. Blue, red, yellow, orange and green phosphors are so called or known by the color of their light emission.

As used in this specification, the terms "substitution" and "doping" refer to adding a certain amount of an element to a material. Usually, by such addition, one element of the material is partially or completely replaced by another element. It should be noted that the various phosphors described in this specification can be written by including different elements in brackets and separated by commas to show substitution or doping, such as ((Ba,Ca,Sr) _1-x Eu _x ) ₂ Si ₅ The case of N ₈ . As understood by those skilled in the art, such symbols mean that the phosphor may contain any or all of those indicated elements in any proportion in the formulation. That is, such symbols for phosphors as above have the same meaning as ((Ba _a Ca _b Sr _1-ab ) _1-x Eu _x ) ₂ Si ₅ N ₈ , where a and b can vary from 0 to 1, for example, and include values of 0 and 1.

This specification describes specific applications in connection with the conversion of ultraviolet (UV), violet or blue radiation produced by LEDs to white light for general lighting purposes. It should be understood, however, that the invention is also applicable to converting radiation from UV, violet and/or blue lasers and other light sources to white light.

Embodiments of the present technology provide phosphor blends that can be used in lighting systems to produce white light suitable for general lighting and other purposes. The phosphor blend includes a first phosphor having the general formula: RE _2-y M _{1+ y} A _2-y Sc _y Si _nw Ge _w O _12+δ :Ce ³⁺ , where RE includes lanthanide ions or Y ³⁺ , M includes Mg, Ca, Sr or Ba, A includes Mg or Zn, and 0≤y≤2, 2.5≤n≤3.5, 0≤w≤1 and -1.5≤δ≤1.5. In one embodiment, the first phosphor may also be represented by the general formula (RE _1-xz Sc _{x Cez} ) ₂ M _3-p A _p Si _nw Ge _w O _12+δ , where RE includes lanthanide ions or Y ³⁺ , M includes Mg, Ca, Sr or Ba, A includes Mg or Zn, and 0≤x<1, 0<z≤0.3, 0≤p≤2, 2.5≤n≤3.5, 0≤w≤1 And -1.5≤δ≤1.5. Advantageously, phosphors made according to these formulations can maintain high emission intensity (quantum efficiency) over a broad temperature range. The phosphors can be used in lighting systems such as LEDs and fluorescent tubes, among others, to generate blue and blue/green light.

In some embodiments, the first phosphor may have the general formula (Ca _1-z Ce _z ) ₃ Sc ₂ Si _nw Ge _w O ₁₂ , where 0<z≦0.3. Specific embodiments of the first phosphor include compositions wherein the Si, Ge components comprise at least about 66% Si ⁴⁺ , at least about 83% Si ⁴⁺ and 100% Si ⁴⁺ . Accordingly, some embodiments include (Ca _{1-z Cez} ) ₃ Sc ₂ (Si _1-c Ge _c ) ₃ O ₁₂ , where c is from 0.67 to 1.

These phosphors having the above formula have reduced luminescence quenching (thermal quenching) at high temperatures compared to many existing phosphors, such as YAG:Ce. Thus, these phosphors maintain their emission intensity over a wide temperature range, which mitigates loss of intensity or lamp color shift as the temperature of the lighting system increases during use.

The phosphor blend also includes a second phosphor that is a red light radiator and a third phosphor that has peak emission over a broad wavelength range of about 520 nm to about 680 nm. The second phosphor may be a compound fluoride, which is a line emitter and generates red light. Suitable examples include complex fluorides doped with Mn ⁴⁺ such as (Na, K, Rb, Cs, NH ₄ ) ₂ [(Ti, Ge, Sn, Si, Zr, Hf)F ₆ ]: Mn ⁴⁺ etc. . In some cases, the Mn ⁴⁺ doped complex fluoride is K ₂ [SiF ₆ ]:Mn ⁴⁺ (“PFS”) used in some exemplary blend examples further below.

The third phosphor may include a phosphor composition having an emission peak in a range of about 520 nanometers (nm) to about 680 nm. The third phosphor is typically a yellow or yellow-orange phosphor with a broad emission range. Non-limiting examples of suitable third phosphors may include garnets, nitrides, and oxynitrides. Table 1 shows some of these examples. Any combination with two or more members selected from garnet, nitride and oxynitride may also be used.

In some embodiments, the third phosphor may be a garnet having the general formula (A, Ce) ₃ M _5-a O _12-3/2a , wherein 0≤a≤0.5, A includes Y, Gd, Tb, La, Sm, Pr or Lu, and M includes Sc, Al or Ga. An example of such a garnet is Y ₃ Al ₅ O ₁₂ :Ce ³⁺ (YAG). The garnet YAG has emission peaks in a broad wavelength range from about 525 nm to about 645 nm.

In some embodiments, the third phosphor may be a nitride having the general formula (A,Eu) _xSiyNz , where 2x+4y _{= 3z} , and A includes Ba, Ca, Sr, or combinations thereof . The nitride can be further doped with cerium. Some embodiments include A ₂ Si ₅ N ₈ :Eu ²⁺ , where A includes Ba, Ca, or Sr. In certain cases, the nitride has the formula ((Ba, Ca, Sr) _1-ab Eu _a Ce _b ) ₂ Si ₅ N ₈ , where 0≦a≦1 and 0≦b≦1. These nitrides emit over a broad wavelength range from about 575 nm to about 675 nm.

In some embodiments, the third phosphor may be an _oxynitride phosphor having the general _{formula ApBqOrNs : R} , where A includes barium, B includes silicon, and R includes europium; and 2 <p<6, 8<q<10, 0.1<r<6, 10<s<15. In these cases, A may also include strontium, calcium, magnesium, or combinations thereof; B may also include aluminum, gallium, germanium, or combinations thereof; and R may also include cerium. In certain cases, the oxynitride phosphor has the formula (Ba, Ca, Sr, Mg) ₄ Si ₉ O _r N _14.66-(2/3)r :Eu such that r is greater than about 1 and less than or equal to about 4 . The emission peaks of these oxynitrides emit in the wavelength range of about 545 nm to about 645 nm.

Table 1

Each of the formulas listed in this specification is independent of every other formula listed. In particular, x, y, z, and other variables that may be used as numerical substitutes in formulas are independent of any use of x, y, z, and other variables that may be present in other formulas or compositions.

When the phosphor material includes a blend of two or more phosphors, the proportion of each of the individual phosphors in the phosphor blend can vary depending on the characteristics of the desired light output (eg, color temperature). Variety. The relative amount of each phosphor in the phosphor blend can be described in terms of spectral weight. The spectral weight is the relative amount each phosphor contributes to the total emission spectrum of the device. The spectrally weighted amounts of all individual phosphors and any residual bleed from the LED source should add up to 100%. In a preferred embodiment, each of the aforementioned phosphors in the blend has a spectral weight of from about 1% to about 70%.

The relative proportions of each phosphor in the phosphor blend can be adjusted to produce predetermined ccx and ccy values on the CIE (International Commission on Illumination) chromaticity diagram when their emissions are blended and used in a lighting fixture of visible light. As stated, white light is preferably produced. The white light can, for example, have a ccx value in the range of about 0.25 to about 0.55, and a ccy value in the range of about 0.25 to about 0.55.

Phosphors used to make phosphor blends can be made by mixing powders of the component compounds and then firing the mixture under a reducing atmosphere. Typically, oxygen-containing compounds of the relevant metals are used. For example, the exemplary phosphor (Ca _0.97 Ce _0.03 ) ₃ Sc ₂ Si ₃ O ₁₂ discussed further in the Examples below can be prepared by mixing appropriate amounts of oxygen-containing compounds of calcium, cerium, scandium, and silicon, and then The mixture is fired under a reducing atmosphere. Silicon can also be provided via silicic acid. After firing, the phosphor may be ball milled or ground to break up any aggregates that may have formed during the firing process. Grinding may be performed after all firing steps are complete, or may be interspersed with additional firing steps.

Non-limiting examples of suitable oxygenates include oxides, hydroxides, alkoxides, carbonates, nitrates, silicates, citrates, oxalates, carboxylates, tartrates, fatty acid salts, nitrites, peroxides and combinations of these compounds. In embodiments containing carboxylates, the carboxylates used may generally have from 1 to 5 carbon atoms, such as formates, ethanoates, propionates, butyrates, and valerates, although carboxylates with Carboxylate with a larger number of carbon atoms. Individual phosphor compositions and blends of these phosphors can be synthesized by any known method, for example as described in US Pat. No. 7,094,362 B2.

In addition, the first phosphor, the second phosphor, and the third phosphor described above may be blended to form a phosphor blend. For example, phosphors can be prepared to contain a first phosphor with the general formula (Ca _0.97 Ce _0.03 ) ₃ Sc ₂ Si ₃ O ₁₂ , a second phosphor with the general formula K ₂ [SiF ₆ ]:Mn ⁴⁺ and The third phosphor of general formula Y ₃ Al ₅ O ₁₂ : Ce ³⁺ (YAG). Activator ions can be used in these phosphors to obtain the desired emission spectrum. As used in this specification, the term "activator ion" refers to an ion (eg, Ce ³⁺ ) incorporated into a phosphor that forms a luminescent center and is responsible for the luminescence of the phosphor. Such ions may include ions of Pr, Sm, Eu, Tb, Dy, Tm, Er, Ho, Nd, Bi, Yb, Pb, Yb, Mn, Ag, Cu, or any combination thereof.

In addition to the synthetic procedures described above, many of the phosphors that can be used in the blends described in this specification are commercially available. For example, the phosphor YAG used in the blend calculations in the prior disclosed phosphor blends is commercially available.

The phosphors listed above are not intended to be limiting. Any other phosphor, commercially and non-commercially available, that forms a non-reactive blend with the phosphor of the present technology can be used in the blend and is considered to be within the scope of the present technology. Furthermore, some additional phosphors may be used, for example, those emitting at wavelengths substantially different from those of the phosphors described in this specification throughout the visible spectral region. These additional phosphors can be used in blends to tailor the white color of the resulting light and produce light sources with improved light quality. In some embodiments, the additional phosphor may have the general formula ((Sr _1-z M _z ) _{1-(x+w) A w} Cex ) ₃ (Al _1-y Si _y )O _{4+y+ 3(xw)} F _1-y-3(xw) phosphor, where 0<x≤0.10 and 0≤y≤0.5, 0≤z≤0.5, 0≤w≤x, A may include Li, Na, K , Rb, or combinations thereof, and M may include Ca, Ba, Mg, Zn, or combinations thereof.

One embodiment of the invention relates to a lighting device comprising a phosphor blend radiatively coupled to a light source. As used in this specification, the term "radiatively coupled" means that elements are related to each other such that at least part of radiation emitted from one element is transmitted to the other element. A combination of light from the light source and light from the phosphor blend can be used to generate white light. For example, white LEDs may be based on blue-emitting InGaN chips. Blue-emitting chips can be coated with a phosphor blend to convert some of the blue radiation to a complementary color, such as yellow-green emission.

Non-limiting examples of lighting devices or devices include devices for excitation by light emitting diodes (LEDs), fluorescent lamps, cathode ray tubes, plasma display devices, liquid crystal displays (LCDs), UV excitation devices (such as color lamps), Lamps for backlit liquid crystal systems, plasma screens, xenon excitation lamps and UV excitation marking systems. These uses are intended to be exemplary only and not exhaustive.

Light emitted from a lighting device can be characterized using a number of standard measurements. The characterization can normalize the data and make comparisons of light emitted by different lighting devices easier to determine. For example, the sum of light from a phosphor and an LED chip provides the color point and correlated color temperature (CCT) with corresponding color coordinates (x and y) in the CIE 1931 chromaticity diagram, and its spectral distribution provides the color rendering index (CRI), as measured by color rendering capabilities. CRI is usually defined as the average of 8 standard color samples (R1-8), which is often referred to as the general color index or Ra. Higher CRI values produce a more "natural" appearance of illuminated objects. By definition, incandescent light has a CRI of 100, while a typical compact fluorescent can have a CRI of about 82. In addition, the photometric or apparent brightness of a light source can also be determined from the spectrum of the emitted light. The photometric measurement is lumens/W-opt, which expresses the number of lumens expressed by 1 watt of light having a specific spectral distribution. Higher lumens/W-opt values indicate that a particular light source appears brighter to a viewer.

Since the light emitted from the combined lighting device components is generally additive, the resulting spectrum of the phosphor blend and/or lighting device can be predicted. For example, the amount of light emitted from each phosphor in the blend can be proportional to the amount of that phosphor within the blend. Thus, the emission spectra from the blends can be modeled and spectral properties such as CCT, CRI, color axes (x and y) and lm/W-opt can be calculated from the predicted emission spectra. Various blends that can be made using the above phosphors are discussed in the Examples below.

Referring now to the drawings, FIG. 1 illustrates one exemplary LED-based lighting device or lamp 10 that may incorporate phosphor blends of the present technology. The LED-based lighting device 10 includes a semiconductor UV or visible light source, such as a light emitting diode (LED) chip 12 . A power lead 14 electrically attached to the LED chip 12 provides an electrical current that causes the LED chip 12 to emit radiation. Leads 14 may comprise leads 16 supported on a thicker housing, or the leads may comprise self-supporting electrodes and the housing leads may be omitted. The leads 14 provide current to the LED chip 12, thus causing the LED chip 12 to emit radiation.

Lamp 10 may comprise any semiconductor blue or UV light source capable of producing white light when radiation emitted by the semiconductor blue or UV light source is directed to a phosphor. In one embodiment, the semiconductor light source comprises a blue light emitting LED doped with various impurities. Accordingly, LED 12 may comprise a semiconductor diode based on any suitable III-V, II-VI or IV-IV semiconductor layer and having an emission wavelength of about 380 to 550 nm. In particular, the LED may contain at least one semiconductor layer comprising GaN, ZnSe or SiC. For example, an LED may comprise a nitride represented by the formula In _i Ga _j Al _k N (where 0≤i; 0≤j; 0≤k and i+j+k=1) having an emission wavelength greater than about 380 nm and less than about 550 nm compound semiconductors. Preferably, the chip is a near UV or blue emitting LED with a peak emission wavelength of about 400 to about 500 nm. Such LED semiconductors are known in the art. For convenience, the light source described in this specification is an LED. However, as used in this specification, the term is intended to cover all semiconductor light sources including, for example, semiconductor laser diodes.

In addition to inorganic semiconductors, the LED chips 12 can be replaced by organic light emitting structures or other light sources. Other types of light sources may be used instead of LEDs, such as gas discharge devices discussed below with respect to FIG. 5 . Examples of gas discharge devices include low, medium and high pressure mercury gas discharge lamps.

The LED chip 12 may be packaged within a housing 18 that encloses the LED chip and an encapsulant material 20 (also referred to as "encapsulant"). Housing 18 may be glass or plastic. Encapsulant 20 may be epoxy, plastic, low temperature glass, polymer, thermoplastic, thermoset, resin, silicone, silicone epoxy, or any other type of LED encapsulation material. Additionally, encapsulant 20 may be spin-on-glass or some other high index material. Typically, the encapsulant material 20 is an epoxy or a polymer material such as silicone. Housing 18 and encapsulant 20 are transparent (ie, substantially optically transmissive) with respect to wavelengths of light generated by LED chip 12 and phosphor material 22 (eg, the phosphor blend of the present technology). However, encapsulant 20 may only be transparent to light from phosphor material 22 if LED chip 12 emits light in the UV spectrum. The LED-based lighting device 10 may include the encapsulant 20 without the outer housing 18 . In the present application, the LED chip 12 may be supported by the housing lead 16 or by a base (not shown) mounted to the housing lead 16 .

The phosphor material 22 is radiatively coupled to the LED chip 12 . In one embodiment, phosphor material 22 may be deposited on LED chip 12 by any suitable method. For example, a solvent-based suspension of the phosphor can be formed and applied as a layer onto the surface of the LED chip 12 . In one contemplated embodiment, a silicone paste with randomly suspended phosphor particles is placed on LED chip 12 . Thus, the phosphor material 22 may be coated on the light emitting surface of the LED chip 12 by coating and drying the phosphor suspension on the LED chip 12 or directly on the light emitting surface of the LED chip 12 . Since housing 18 and encapsulant 20 are generally transparent, emitted light 24 from LED chip 12 and phosphor material 22 will transmit through those elements. Although not intended to be limiting, in one embodiment, phosphor material 22 may have a median particle size as measured by light scattering of about 1 to about 15 microns.

A second structure of a phosphor blend that can incorporate the technology of the present invention is shown in cross-section in FIG. 2 . The structure in FIG. 2 is similar to that of FIG. 1 , except that the phosphor material 22 is interspersed within the encapsulant 20 rather than being formed directly on the LED chip 12 . Phosphor material 22 may be dispersed within a single region of encapsulant 20 or throughout the entire volume of encapsulant 20 . Radiation 26 emitted by LED chip 12 mixes with light emitted by phosphor material 22 , and the mixed light is visible through transparent encapsulant 20 , shown as emitted light 24 .

Encapsulant 20 with dispersed phosphor material 22 may be formed by a variety of suitable plastic processing techniques. For example, the phosphor material 22 can be combined with a polymer precursor, molded around the LED chip 12, and then cured to form the solid encapsulant 20 with the phosphor material 22 dispersed. In another technique, the phosphor material 22 can be blended into a molten encapsulant 20 (such as polycarbonate) formed around the LED chip 12 and then allowed to cool. Processing techniques for molding plastics that can be used, such as injection molding, are known in the art.

Figure 3 shows a cross-section of a structure of phosphor material 22 that may incorporate the techniques of the present invention. The structure shown in FIG. 3 is similar to that of FIG. 1 , except that phosphor material 22 may be coated on the surface of housing 18 instead of being formed on LED chip 12 . Typically, phosphor material 22 is coated on the interior surface of housing 18 , although phosphor material 22 may be coated on the exterior surface of housing 18 if desired. Phosphor material 22 may be coated on the entire surface of housing 18 , or only on top of the surface of housing 18 . Radiation 26 emitted by LED chip 12 mixes with light emitted by phosphor material 22 , and the mixed light appears as emitted light 24 .

The structures discussed in Figures 1-3 may be combined with phosphor material in any two or all three locations or in any other suitable location, such as separate from the housing or integrated into the LED. Additionally, different phosphor blends can be used in different parts of the structure.

In any of the above structures, the LED-based lighting device 10 may also include a plurality of particles (not shown) to scatter or diffuse the emitted light. These scattering particles are usually embedded in the encapsulant 20 . Scattering particles may include, for example, particles made of Al ₂ O ₃ (aluminum oxide) or TiO ₂ . Scattering particles can effectively scatter light emitted from LED chip 12 and are typically selected to have a negligible amount of absorption.

In addition to the above structure, the LED chip 12 may be installed in the reflective cup 28 as shown by the cross-section shown in FIG. 4 . Reflective cup 28 may be made of or coated with a reflective material such as alumina, titania, or other dielectric powders known in the art. Typically, reflective surfaces can be made of Al ₂ O ₃ . The remainder of the structure of the LED-based lighting device 10 of FIG. 4 is the same as in previous figures, and includes two leads 16 , a wire 30 electrically connecting the LED chip 12 to one of the leads 16 , and an encapsulant 20 . The reflective cup 28 can conduct current to energize the LED chip 12 or a second wire 32 can be used to energize the LED chip 12 . Phosphor material 22 may be dispersed throughout encapsulant 20 as described above, or may be dispersed in a smaller transparent shell 34 formed within reflective cup 28 . Generally, the transparent shell 34 can be made from the same material as the encapsulant 20 . The use of transparent shell 34 within encapsulant 20 is advantageous in that a smaller amount of phosphor material 22 may be required than if the phosphor were dispersed throughout encapsulant 20 . Encapsulant 20 may contain particles (not shown) of light scattering material to diffuse emitted light 24 as previously described.

FIG. 5 is a perspective view of a lighting device 36 based on a gas discharge device, such as a fluorescent lamp, that can use the phosphor blend of the technology of the present invention. Lamp 36 may include an evacuated sealed envelope 38 , an excitation system 42 for generating UV radiation located within envelope 38 , and phosphor material 22 disposed within envelope 38 . End caps 40 are attached to either end of the housing 38 to seal the housing 38 .

In a typical fluorescent lamp, phosphor material 22 , such as a phosphor blend of the present technology, may be disposed on the inner surface of envelope 38 . An excitation system 42 for generating UV radiation may include an electron generator 44 for generating energetic electrons and a fill gas 46 configured to absorb the energy of the energetic electrons and emit UV light. For example, fill gas 46 may include mercury vapor that absorbs energy from energetic electrons and emits UV light. Fill gas 46 may include a noble gas such as argon, krypton, etc. in addition to mercury vapor. Electron generator 44 may be a filament of a metal with a low work function (eg, less than 4.5 eV), such as tungsten, or a filament coated with an alkaline earth metal oxide. Pins 48 may be provided to supply electrical power to the electron generator 44 . The filament is coupled to a high voltage source to generate electrons from its surface.

The phosphor material 22 is radiatively coupled to UV light from an excitation system 42 . As previously stated, radiative coupling means that the phosphor material 22 is associated with the excitation system 42 such that radiation of UV light from the excitation system 42 is transmitted to the phosphor material 22 . Accordingly, phosphor materials that are radiatively coupled to excitation system 42 can absorb radiation, such as UV light emitted by excitation system 42, and respond by emitting longer wavelengths, such as blue, blue-green, green, yellow, or red light. . Longer wavelength light may be visible when emitted light 24 is transmitted through housing 38 . Housing 38 is typically made of a transparent material such as glass or quartz. Glass is often used as an envelope 38 in fluorescent lamps because of its transmission spectrum which blocks a substantial portion of "short wave" UV radiation, ie, light with wavelengths less than about 300 nm.

Particulate materials such as TiO ₂ or Al ₂ O ₃ may be used in conjunction with phosphor blend 22 to diffuse light generated by light source 36 . Such a light diffusing material may be included with the phosphor blend 22 or may be provided separately as a layer between the inner surface of the housing 38 and the phosphor blend 22 . For fluorescent tubes, it may be advantageous for the diffusing material to have a median particle size of from about 10 nm to about 400 nm.

Although the lighting device or lamp 36 shown in FIG. 5 has a rectilinear housing 38, other housing shapes may be used. For example, a compact fluorescent lamp may have a housing 38 with one or more bends or a spiral shape, with power pins 48 provided at one end of the lamp 36 .

By assigning appropriate spectral weights to each phosphor, spectral blends can be generated to cover the relevant portion of the color space of white light. Specific examples thereof are shown below. The appropriate amount of each phosphor to include in the blend can be determined for each desired CCT, CRI, and color point. Thus, phosphor blends can be tailored to produce virtually any CCT or color point with a correspondingly high CRI. Of course, the color of each phosphor will depend on its exact composition (such as the relative amounts of Ba, Ca, Sr, and Eu in a nitride phosphor), which can change the color of the phosphor to what it must be renamed. degree. However, determining the same or similar characteristic illuminators required for changes in spectral weights to produce such changes is immaterial and can be achieved by those skilled in the art using various methods such as Design of Experiments (DOE) or other strategies.

Lamps with high luminance and general CRI values greater than about 80 can be provided for the low range of color temperatures of interest (2500K to 4000K) for general lighting by using the present invention, in particular the blends described in this specification. In some blends, the CRI values are close to the theoretical maximum of 100. Additionally, the _R9 values for these blends can exceed about 90 and are also close to the theoretical maximum. Tables 1 and 2 show the luminosity, CRI values and _R9 values of the respective blends at CCT values of 2700K and 3000K, respectively.

example

The following examples are illustrative only and should not be construed as any kind of limitation on the scope of the claimed invention.

Each phosphor composition according to the formulation listed in Table 2 was prepared. The emission spectra of the individual phosphors were obtained and used in calculations to predict the emission spectra of the individual blends present in Table 3. In addition, the calculation also includes any visible light emitted by the light source. Figures 6 and 7 show the predicted emission spectra for Examples 1 and 2 of the blends in Table 3. Premeasurements of each phosphor based on spectral weights are shown in Table 4 along with the spectral contribution from the emission of the light source (eg blue LED with peak wavelengths of 430nm, 440nm and 450nm). In addition, the spectral properties calculated from the predicted spectra of these blends are also shown in Table 4. Figures 6 and 7 correspond to blend examples Nos. 4 and 3 of Table 4, respectively. Advantageously, these blends produce white light with high luminosity, high CRI values and low CCT adjustable between 2500K and 3000K.

Table 2

table 3

Table 4

Table 4

While only certain features of the invention have been shown and described in the specification, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

Claims (9)

1. a kind of phosphor material, it includes the blend of following substances：

First phosphor, first phosphor is included with general formula R E_2-yM_1+yA_2-ySc_ySi_n-wGe_wO_12+δ：Ce³⁺Composition, its Middle RE is selected from lanthanide ion or Y³⁺, selected from Mg, Ca, Sr or Ba, A is selected from Mg or Zn, and 0≤y≤2,2.5≤n≤3.5,0≤w to M ≤ 1 and -1.5≤δ≤1.5,

Second phosphor, second phosphor includes formula A₂[MF₆]：Mn⁴⁺Doping manganese (Mn⁴⁺) composite fluoride, its Middle A is selected from Na, K, Rb, Cs, NH₄Or combinations thereof, and M is selected from Si, Ti, Zr, Mn or combinations thereof, and

3rd phosphor, the 3rd phosphor is included in the range of about 520nm to about 680nm the phosphor group with emission peak Into.

2. phosphor material according to claim 1, it is characterised in that first phosphor is included with formula (Ca_1-zCe_z)₃Sc₂Si_n-wGe_wO₁₂Composition, wherein 0 ＜ z≤0.3.

3. phosphor material according to claim 1, it is characterised in that the 3rd phosphor is selected from garnet, nitridation Thing, oxynitride or combinations thereof.

4. phosphor material according to claim 3, it is characterised in that the 3rd phosphor include with formula (A, Ce)₃M_5-aO_12-3/2aGarnet, wherein 0≤a≤0.5, A is selected selected from Y, Gd, Tb, La, Sm, Pr, Lu or combinations thereof, and M From Sc, Al, Ga or combinations thereof.

5. phosphor material according to claim 3, it is characterised in that the 3rd phosphor include with formula (A, Eu)_xSi_yN_zNitride, wherein 2x+4y=3z, and A is selected from Ba, Ca, Sr or combinations thereof.

6. phosphor material according to claim 5, it is characterised in that the 3rd phosphor includes A₂Si₅N₈：Eu²⁺, Ce³⁺, wherein A is selected from Ba, Ca, Sr or combinations thereof.

7. phosphor material according to claim 3, it is characterised in that the 3rd phosphor is included with formula A_pB_qO_rN_s：The oxynitride of R, wherein A are selected from barium, and B is selected from silicon, and R is selected from europium；And the ＜ r of 2 ＜ p ＜, 6,8 ＜ q ＜ 10,0.1 The ＜ s ＜ 15 of ＜ 6,10.

8. a kind of illuminator, it includes：Light source and phosphor material, the light source can be transmitted in about 400 nanometers to about 480 Radiation in nanometer range, the phosphor material radiation is attached to the light source, and including the blend of following substances：

First phosphor, first phosphor is included with general formula R E_2-yM_1+yA_2-ySc_ySi_n-wGe_wO_12+δ：Ce³⁺Composition, its Middle RE is selected from lanthanide ion or Y³⁺, wherein M is selected from Mg, Ca, Sr or Ba, and A is selected from Mg or Zn, and wherein 0≤y≤2, and 2.5≤n≤ 3.5,0≤w≤1 and -1.5≤δ≤1.5,

Second phosphor, second phosphor includes formula A₂[MF₆]：Mn⁴⁺Doping manganese (Mn⁴⁺) composite fluoride, its Middle A is selected from Na, K, Rb, Cs, NH₄Or combinations thereof, and M is selected from Si, Ti, Zr, Mn or combinations thereof, and

3rd phosphor, the 3rd phosphor is included in the range of about 520nm to about 680nm the phosphor group with emission peak Into.

9. illuminator according to claim 8, it is characterised in that the light source includes luminaire LED.